138 70NITES. 



Blatter, 1880. Twenty-eight species are therein enumerated to 

 which a few have since been added. The distribution is from 

 the Canary Islands to Japan, including the Mediterranean coast 

 of Africa, all Europe, and Asia north of the Himalayas. The 

 species are small, seldom exceeding five millimetres in diameter, 

 with narrow umbilicus or imperforate, the whorls rather narrow, 

 the form flattened or sublenticular, glassy and transparent. 

 H. crystalline., Miill., is taken as the typical form, whilst two 

 subsections are grouped with H. diaphana and H. hydatina 

 respectively. 



I. Group of H. cryttallina. 



H. CRYSTALLINA, Muller. PL 46, figs. 3-8. 



Shell perforate, depressed, diaphanous, smooth, shining; 

 whorls 4-4^, flattened. Diam. 3-4 mill. 



Iceland, Europe, Madeira, Canaries. 



It is H.pellucida, Pennant; H. vitrea, Brown ; H. eburnea, 

 Hartman, and H. diaphana, Charp. 



Var. COMPLANATA, Jeffreys. 



Shell flatter, the last whorl much wider. 



Var. NITIDISSIMA, Baudon. 



Smaller, fragile, very crystalline, translucent, vitreous, very 

 slightly greenish, brilliant. Dept. Oise, France. 



Var. SUBTERRANEA, Bourg. Figs 6-8. 



Umbilicus a little wider, shell flattened above, smooth or 

 elegantly slightly striulate at the suture; whorls 5, suture deep; 

 lip whitish thickened within. Diam. 3 mill. 



Dept. de VAube, France, Germany, Sweden. 



Mabille has made a new species, H. secernanda, from the figures 

 of this species in Albers' Malacol. Maderensis, but as the figures 

 of this work are often very inaccurate they should scarcely be 

 accepted for differential characters. On the other hand a single 

 specimen found at Fuerteventura, in the Canaries, has the um- 

 bilicus a trifle larger than in those from the other islands, and 

 although Wollaston admits the importation of the species from 

 Europe, he calls this Var. Fuerteventurse. 



